Packet-based communication system and method

ABSTRACT

A system and method for facilitating communication of packets between one or more applications residing on a first computing device and at least one second computing device. The system comprises a connection manager adapted to receive packets from the at least one second computing device, and a packet cache for storing packets received by the connection manager. The connection manager, upon receiving a packet from a second computing device, transmits the packet to the packet cache for storage and notifies each of the applications of receipt of the packet. Subsequently, the packet is retrievable from the packet cache by a notified application, and verification that the packet is intended for communication to the notified application is made.

FIELD OF THE INVENTION

The present invention relates generally to packet-based communicationsystems, and more specifically to a system and method for managingcommunications between computing devices.

BACKGROUND OF THE INVENTION

Internet protocols exist that govern packet-based communications betweena host computing device and a client computing device. For example, inan Internet Protocol Security (IPsec) based virtual private network(VPN), packets relating to the exchange of keys used for encrypting andauthenticating data, and packets relating to the exchange of the dataitself are typically communicated between the host and client computingdevices. In establishing a connection between the host and clientcomputing devices, the keys associated with the connection are generallyexchanged between the devices before the data is exchanged.

In some circumstances, multiple components (e.g. applications orapplication threads) residing on a client computing device may need tobe in communication with one or more host computing devices within agiven time period. Multiple connections between the host and clientcomputing devices, over the same port or over different ports, may needto be established to facilitate such communications. To properly managethe connections, communications associated with the different componentsneed to be kept separate, since they are potentially at different stages(e.g. of a key or data exchange).

Furthermore, the connections established between the host and clientcomputing devices generally have limited lifetimes. This typicallyresults in a periodic change of keys associated with each connection.Therefore, to properly manage the connections, communications protectedby different security parameters (e.g. different keys), over one ormultiple ports, also need to be kept separate.

The manner in which communications over multiple connections between aclient computing device and one or more host computing devices in a VPNshould be managed, however, is not explicitly addressed by currentprotocols commonly in use, such as IPsec.

SUMMARY OF THE INVENTION

Embodiments of the invention are generally directed to a system andmethod for managing communications between computing devices thatfacilitate packet-based communications over multiple connections betweena client computing device and one or more host computing devices.

In one broad aspect of the invention, there is provided a system forfacilitating communication of packets between one or more applicationsresiding on a first computing device and at least one second computingdevice, the system comprising: a connection manager adapted to receivepackets from the at least one second computing device; and a packetcache, coupled to the connection manager, for storing packets receivedby the connection manager; wherein, in operation, upon receiving apacket from a second computing device, the connection manager transmitsthe packet to the packet cache for storage and notifies each of the oneor more applications of receipt of the packet; wherein the packet isretrievable from the packet cache by a notified application, andverification that the packet is intended for communication to thenotified application is made.

In another broad aspect of the invention, there is provided a method offacilitating communication of packets between one or more applicationsresiding on a first computing device and at least one second computingdevice, the method comprising the steps of: receiving a packet from asecond computing device; transmitting the received packet to a packetcache for storage; notifying each of the one or more applications ofreceipt of the received packet; upon request of a notified application,retrieving the received packet from the packet cache; and verifying ifthe received packet is intended for communication to the notifiedapplication.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of embodiments of the invention, and to showmore clearly how it may be carried into effect, reference will now bemade, by way of example, to the accompanying drawings in which:

FIG. 1 is a block diagram of a mobile device in one exampleimplementation;

FIG. 2 is a block diagram of a communication subsystem component of themobile device of FIG. 1;

FIG. 3 is a block diagram of a node of a wireless network;

FIG. 4 is a block diagram of an example topology of a virtual privatenetwork;

FIG. 5 is a block diagram of a mobile device comprising componentsenabling packet-based communication with a host system in an embodimentof the invention; and

FIG. 6 is a flowchart illustrating steps in a method of facilitatingcommunication of packets between one or more applications residing on afirst computing device and at least one second computing device in anembodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Some embodiments of the invention make use of a mobile station. A mobilestation is a two-way communication device with advanced datacommunication capabilities having the capability to communicate withother computer systems, and is also referred to herein generally as amobile device. A mobile device may also include the capability for voicecommunications. Depending on the functionality provided by a mobiledevice, it may be referred to as a data messaging device, a two-waypager, a cellular telephone with data messaging capabilities, a wirelessInternet appliance, or a data communication device (with or withouttelephony capabilities). A mobile device communicates with other devicesthrough a network of transceiver stations.

To aid the reader in understanding the structure of a mobile device andhow it communicates with other devices, reference is made to FIGS. 1through 3.

Referring first to FIG. 1, a block diagram of a mobile device in oneexample implementation is shown generally as 100. Mobile device 100comprises a number of components, the controlling component beingmicroprocessor 102. Microprocessor 102 controls the overall operation ofmobile device 100. Communication functions, including data and voicecommunications, are performed through communication subsystem 104.Communication subsystem 104 receives messages from and sends messages toa wireless network 200. In this example implementation of mobile device100, communication subsystem 104 is configured in accordance with theGlobal System for Mobile Communication (GSM) and General Packet RadioServices (GPRS) standards. The GSM/GPRS wireless network is usedworldwide and it is expected that these standards will be supersededeventually by Enhanced Data GSM Environment (EDGE) and Universal MobileTelecommunications Service (UMTS). New standards are still beingdefined, but it is believed that they will have similarities to thenetwork behaviour described herein, and it will also be understood bypersons skilled in the art that the invention is intended to use anyother suitable standards that are developed in the future. The wirelesslink connecting communication subsystem 104 with network 200 representsone or more different Radio Frequency (RF) channels, operating accordingto defined protocols specified for GSM/GPRS communications. With newernetwork protocols, these channels are capable of supporting both circuitswitched voice communications and packet switched data communications.

Although the wireless network associated with mobile device 100 is aGSM/GPRS wireless network in one example implementation of mobile device100, other wireless networks may also be associated with mobile device100 in variant implementations. Different types of wireless networksthat may be employed include, for example, data-centric wirelessnetworks, voice-centric wireless networks, and dual-mode networks thatcan support both voice and data communications over the same physicalbase stations. Combined dual-mode networks include, but are not limitedto, Code Division Multiple Access (CDMA) or CDMA2000 networks, GSM/GPRSnetworks (as mentioned above), and future third-generation (3G) networkslike EDGE and UMTS. Some older examples of data-centric networks includethe Mobitex™ Radio Network and the DataTAC™ Radio Network. Examples ofolder voice-centric data networks include Personal Communication Systems(PCS) networks like GSM and Time Division Multiple Access (TDMA)systems.

Microprocessor 102 also interacts with additional subsystems such as aRandom Access Memory (RAM) 106, flash memory 108, display 110, auxiliaryinput/output (I/O) subsystem 112, serial port 114, keyboard 116, speaker118, microphone 120, short-range communications 122 and other devices124.

Some of the subsystems of mobile device 100 performcommunication-related functions, whereas other subsystems may provide“resident” or on-device functions. By way of example, display 110 andkeyboard 116 may be used for both communication-related functions, suchas entering a text message for transmission over network 200, anddevice-resident functions such as a calculator or task list. Operatingsystem software used by microprocessor 102 is typically stored in apersistent store such as flash memory 108, which may alternatively be aread-only memory (ROM) or similar storage element (not shown). Thoseskilled in the art will appreciate that the operating system, specificdevice applications, or parts thereof, may be temporarily loaded into avolatile store such as RAM 106.

Mobile device 100 may send and receive communication signals overnetwork 200 after required network registration or activation procedureshave been completed. Network access is associated with a subscriber oruser of a mobile device 100. To identify a subscriber, mobile device 100requires a Subscriber Identity Module or “SIM” card 126 to be insertedin a SIM interface 128 in order to communicate with a network. SIM 126is one type of a conventional “smart card” used to identify a subscriberof mobile device 100 and to personalize the mobile device 100, amongother things. Without SIM 126, mobile device 100 is not fullyoperational for communication with network 200. By inserting SIM 126into SIM interface 128, a subscriber can access all subscribed services.Services could include: web browsing and messaging such as email, voicemail, Short Message Service (SMS), and Multimedia Messaging Services(MMS). More advanced services may include: point of sale, field serviceand sales force automation. SIM 126 includes a processor and memory forstoring information. Once SIM 126 is inserted in SIM interface 128, itis coupled to microprocessor 102. In order to identify the subscriber,SIM 126 contains some user parameters such as an International MobileSubscriber Identity (IMSI). An advantage of using SIM 126 is that asubscriber is not necessarily bound by any single physical mobiledevice. SIM 126 may store additional subscriber information for a mobiledevice as well, including datebook (or calendar) information and recentcall information.

Mobile device 100 is a battery-powered device and includes a batteryinterface 132 for receiving one or more rechargeable batteries 130.Battery interface 132 is coupled to a regulator (not shown), whichassists battery 130 in providing power V+ to mobile device 100. Althoughcurrent technology makes use of a battery, future technologies such asmicro fuel cells may provide the power to mobile device 100.

Microprocessor 102, in addition to its operating system functions,enables execution of software applications on mobile device 100. A setof applications that control basic device operations, including data andvoice communication applications, will normally be installed on mobiledevice 100 during its manufacture. Another application that may beloaded onto mobile device 100 would be a personal information manager(PIM). A PIM has functionality to organize and manage data items ofinterest to a subscriber, such as, but not limited to, e-mail, calendarevents, voice mails, appointments, and task items. A PIM application hasthe ability to send and receive data items via wireless network 200. PIMdata items may be seamlessly integrated, synchronized, and updated viawireless network 200 with the mobile device subscriber's correspondingdata items stored and/or associated with a host computer system. Thisfunctionality creates a mirrored host computer on mobile device 100 withrespect to such items. This can be particularly advantageous where thehost computer system is the mobile device subscriber's office computersystem.

Additional applications may also be loaded onto mobile device 100through network 200, auxiliary I/O subsystem 112, serial port 114,short-range communications subsystem 122, or any other suitablesubsystem 124. This flexibility in application installation increasesthe functionality of mobile device 100 and may provide enhancedon-device functions, communication-related functions, or both. Forexample, secure communication applications may enable electroniccommerce functions and other such financial transactions to be performedusing mobile device 100.

Serial port 114 enables a subscriber to set preferences through anexternal device or software application and extends the capabilities ofmobile device 100 by providing for information or software downloads tomobile device 100 other than through a wireless communication network.The alternate download path may, for example, be used to load anencryption key onto mobile device 100 through a direct and thus reliableand trusted connection to provide secure device communication.

Short-range communications subsystem 122 provides for communicationbetween mobile device 100 and different systems or devices, without theuse of network 200. For example, subsystem 122 may include an infrareddevice and associated circuits and components for short-rangecommunication. Examples of short range communication would includestandards developed by the Infrared Data Association (IrDA), Bluetooth,and the 802.11 family of standards developed by IEEE.

In use, a received signal such as a text message, an e-mail message, orweb page download will be processed by communication subsystem 104 andinput to microprocessor 102. Microprocessor 102 will then process thereceived signal for output to display 110 or alternatively to auxiliaryI/O subsystem 112. A subscriber may also compose data items, such ase-mail messages, for example, using keyboard 116 in conjunction withdisplay 110 and possibly auxiliary I/O subsystem 112. Auxiliarysubsystem 112 may include devices such as: a touch screen, mouse, trackball, infrared fingerprint detector, or a roller wheel with dynamicbutton pressing capability. Keyboard 116 is an alphanumeric keyboardand/or telephone-type keypad. A composed item may be transmitted overnetwork 200 through communication subsystem 104.

For voice communications, the overall operation of mobile device 100 issubstantially similar, except that the received signals would be outputto speaker 118, and signals for transmission would be generated bymicrophone 120. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on mobiledevice 100. Although voice or audio signal output is accomplishedprimarily through speaker 118, display 110 may also be used to provideadditional information such as the identity of a calling party, durationof a voice call, or other voice call related information.

Referring now to FIG. 2, a block diagram of the communication subsystemcomponent 104 of FIG. 1 is shown. Communication subsystem 104 comprisesa receiver 150, a transmitter 152, one or more embedded or internalantenna elements 154, 156, Local Oscillators (LOs) 158, and a processingmodule such as a Digital Signal Processor (DSP) 160.

The particular design of communication subsystem 104 is dependent uponthe network 200 in which mobile device 100 is intended to operate, thusit should be understood that the design illustrated in FIG. 2 servesonly as one example. Signals received by antenna 154 through network 200are input to receiver 150, which may perform such common receiverfunctions as signal amplification, frequency down conversion, filtering,channel selection, and analog-to-digital (A/D) conversion. A/Dconversion of a received signal allows more complex communicationfunctions such as demodulation and decoding to be performed in DSP 160.In a similar manner, signals to be transmitted are processed, includingmodulation and encoding, by DSP 160. These DSP-processed signals areinput to transmitter 152 for digital-to-analog (D/A) conversion,frequency up conversion, filtering, amplification and transmission overnetwork 200 via antenna 156. DSP 160 not only processes communicationsignals, but also provides for receiver and transmitter control. Forexample, the gains applied to communication signals in receiver 150 andtransmitter 152 may be adaptively controlled through automatic gaincontrol algorithms implemented in DSP 160.

The wireless link between mobile device 100 and a network 200 maycontain one or more different channels, typically different RF channels,and associated protocols used between mobile device 100 and network 200.A RF channel is a limited resource that must be conserved, typically dueto limits in overall bandwidth and limited battery power of mobiledevice 100.

When mobile device 100 is fully operational, transmitter 152 istypically keyed or turned on only when it is sending to network 200 andis otherwise turned off to conserve resources. Similarly, receiver 150is periodically turned off to conserve power until it is needed toreceive signals or information (if at all) during designated timeperiods.

Referring now to FIG. 3, a block diagram of a node of a wireless networkis shown as 202. In practice, network 200 comprises one or more nodes202. Mobile device 100 communicates with a node 202 within wirelessnetwork 200. In the example implementation of FIG. 3, node 202 isconfigured in accordance with General Packet Radio Service (GPRS) andGlobal Systems for Mobile (GSM) technologies. Node 202 includes a basestation controller (BSC) 204 with an associated tower station 206, aPacket Control Unit (PCU) 208 added for GPRS support in GSM, a MobileSwitching Center (MSC) 210, a Home Location Register (HLR) 212, aVisitor Location Registry (VLR) 214, a Serving GPRS Support Node (SGSN)216, a Gateway GPRS Support Node (GGSN) 218, and a Dynamic HostConfiguration Protocol (DHCP) 220. This list of components is not meantto be an exhaustive list of the components of every node 202 within aGSM/GPRS network, but rather a list of components that are commonly usedin communications through network 200.

In a GSM network, MSC 210 is coupled to BSC 204 and to a landlinenetwork, such as a Public Switched Telephone Network (PSTN) 222 tosatisfy circuit switched requirements. The connection through PCU 208,SGSN 216 and GGSN 218 to the public or private network (Internet) 224represents the data path for GPRS capable mobile devices. In a GSMnetwork extended with GPRS capabilities, BSC 204 also contains a PacketControl Unit (PCU) 208 that connects to SGSN 216 to controlsegmentation, radio channel allocation and to satisfy packet switchedrequirements. To track mobile device location and availability for bothcircuit switched and packet switched management, HLR 212 is sharedbetween MSC 210 and SGSN 216. Access to VLR 214 is controlled by MSC210.

Station 206 is a fixed transceiver station. Station 206 and BSC 204together form the fixed transceiver equipment. The fixed transceiverequipment provides wireless network coverage for a particular coveragearea commonly referred to as a “cell”. The fixed transceiver equipmenttransmits communication signals to and receives communication signalsfrom mobile devices within its cell via station 206. The fixedtransceiver equipment normally performs such functions as modulation andpossibly encoding and/or encryption of signals to be transmitted to themobile device in accordance with particular, usually predetermined,communication protocols and parameters, under control of its controller.The fixed transceiver equipment similarly demodulates and possiblydecodes and decrypts, if necessary, any communication signals receivedfrom mobile device 100 within its cell. Communication protocols andparameters may vary between different nodes. For example, one node mayemploy a different modulation scheme and operate at differentfrequencies than other nodes.

For all mobile devices 100 registered with a specific network, permanentconfiguration data such as a user profile is stored in HLR 212. HLR 212also contains location information for each registered mobile device andcan be queried to determine the current location of a mobile device. MSC210 is responsible for a group of location areas and stores the data ofthe mobile devices currently in its area of responsibility in VLR 214.Further VLR 214 also contains information on mobile devices that arevisiting other networks. The information in VLR 214 includes part of thepermanent mobile device data transmitted from HLR 212 to VLR 214 forfaster access. By moving additional information from a remote HLR 212node to VLR 214, the amount of traffic between these nodes can bereduced so that voice and data services can be provided with fasterresponse times and at the same time requiring less use of computingresources.

SGSN 216 and GGSN 218 are elements added for GPRS support; namely packetswitched data support, within GSM. SGSN 216 and MSC 210 have similarresponsibilities within wireless network 200 by keeping track of thelocation of each mobile device 100. SGSN 216 also performs securityfunctions and access control for data traffic on network 200. GGSN 218provides internetworking connections with external packet switchednetworks and connects to one or more SGSN's 216 via an Internet Protocol(IP) backbone network operated within the network 200. During normaloperations, a given mobile device 100 must perform a “GPRS Attach” toacquire an IP address and to access data services. This requirement isnot present in circuit switched voice channels as Integrated ServicesDigital Network (ISDN) addresses are used for routing incoming andoutgoing calls. Currently, all GPRS capable networks use private,dynamically assigned IP addresses, thus requiring a DHCP server 220connected to the GGSN 218. There are many mechanisms for dynamic IPassignment, including using a combination of a Remote AuthenticationDial-In User Service (RADIUS) server and DHCP server. Once the GPRSAttach is complete, a logical connection is established from a mobiledevice 100, through PCU 208, and SGSN 216 to an Access Point Node (APN)within GGSN 218. The APN represents a logical end of an IP tunnel thatcan either access direct Internet compatible services or private networkconnections. The APN also represents a security mechanism for network200, insofar as each mobile device 100 must be assigned to one or moreAPNs and mobile devices 100 cannot exchange data without firstperforming a GPRS Attach to an APN that it has been authorized to use.The APN may be considered to be similar to an Internet domain name suchas “myconnection.wireless.com”.

Once the GPRS Attach is complete, a tunnel is created and all traffic isexchanged within standard IP packets using any protocol that can besupported in IP packets. This includes tunneling methods such as IP overIP as in the case with some IPSecurity (Ipsec) connections used withVirtual Private Networks (VPN). These tunnels are also referred to asPacket Data Protocol (PDP) Contexts and there are a limited number ofthese available in the network 200. To maximize use of the PDP Contexts,network 200 will run an idle timer for each PDP Context to determine ifthere is a lack of activity. When a mobile device 100 is not using itsPDP Context, the PDP Context can be deallocated and the IP addressreturned to the IP address pool managed by DHCP server 220.

In one example implementation of the invention in which a VPN isestablished, the IP packets are exchanged with a host system 250 overthe public or private network (e.g. Internet) 224 (also referred toherein as a “shared network” or “shared network infrastructure”). Thisexample implementation is described in further detail with reference toFIG. 4.

Referring now to FIG. 4, a block diagram of an example topology of avirtual private network is shown. In this example topology, mobiledevice 100 communicates with host system 250 through a node 202 ofwireless network 200 and a shared network infrastructure 224 such as aservice provider network or the public Internet. Host system 250 may bea host or desktop computing device, or it may consist of a network ofcomputing devices. Access to host system 250 may be provided through arouter 252, and computing devices of host system 250 may operate fromwithin a firewall [not shown].

In a variant implementation, host system 250 may comprise a wireless VPNrouter to facilitate data exchange between the host system 250 andmobile device 100. The concept of a wireless VPN router is new in thewireless industry and implies that a VPN connection can be establisheddirectly through a specific wireless network to a mobile device 100. Thepossibility of using a wireless VPN router has only recently beenavailable and could be used when the new Internet Protocol (IP) Version6 (IPV6) arrives into IP-based wireless networks. This new protocol willprovide enough IP addresses to dedicate an IP address to every mobiledevice 100, making it possible to push information to a mobile device100 at any time. An advantage of using a wireless VPN router is that itcould be an off-the-shelf VPN component, not requiring a separatewireless gateway and separate wireless infrastructure to be used. A VPNconnection would preferably be a Transmission Control Protocol (TCP)/IPor User Datagram Protocol (UDP)/IP connection to deliver the messagesdirectly to the mobile device 100 in this variant implementation.

Embodiments of the invention may be employed in implementations wherepackets are exchanged in communications between mobile device 100 andhost system 250. However, it will be understood by persons skilled inthe art that certain embodiments of the invention may be employed inimplementations where computing devices other than mobile device 100 areto communicate with host system 250, within a VPN or otherwise.

For instance, embodiments of the invention may be employed in variousdifferent types of VPN topologies. For example, an intranet site-to-siteVPN may connect a local area network at a remote office 254 or otherremote location (through which access may be provided through a router252) to host system 250 over the shared network 224. By way of furtherexample, a remote-access VPN may connect remote users at a home office256 or other mobile user 258 to host system 250, via a point-of-presence(POP) connection 260 through which the shared network 224 is accessed(e.g. by dial-up access). Other sites [not shown] may also communicatewith host system 250 through an extranet-based VPN, as a furtherexample.

Each of the above VPN applications is supported by secure,network-to-network, host-to-network, or host-to-host tunnels, which arevirtual point-to-point connections. Tunnels may exist at severalprotocol layers. For example, certain tunnels provide IP-based virtualconnections. In this approach, normal IP packets are routed betweentunnel endpoints that are separated by some intervening networktopology. Tunneled packets are wrapped inside headers that providemessage integrity and confidentiality. In this regard, IPsec is a set ofprotocols defined by the Internet Engineering Task Force (IETF) that maybe used to provide IP security at the network layer.

An IPsec-based VPN is made up of two parts: an Internet Key Exchangeprotocol (IKE) and IPsec protocols for data exchange. The first part,IKE, is the initial negotiation phase where the two VPN endpoints agreeon which methods will be used to provide security for the underlying IPtraffic. Session keys for the encryption and authentication algorithmsemployed are distributed. IKE is also used to manage connections bydefining a set of security associations for each connection. The secondpart, the IPsec protocols, describes how the data will be processed.These protocols include Authentication Header (AH) and EncapsulatingSecurity Payload (ESP), for example. The foregoing is not intended to bea complete description of IPsec and VPNs, as will be understood bypersons skilled in the art.

It will also be understood by persons skilled in the art thatimplementations of embodiments of the invention may be employed forapplications other than in the establishment of VPNs, and with the useof other packet-based communication protocols not mentioned above.

Referring to FIG. 5, a block diagram of a mobile device comprisingcomponents enabling packet-based communication with a host system in anembodiment of the invention is shown. For ease of exposition, only asubset of components of the mobile device is illustrated in describingthis embodiment of the invention.

As indicated earlier, although this embodiment is described withreference to a mobile device, applications of the invention are notlimited to implementations employing mobile devices. In variantembodiments of the invention, a computing device other than a mobiledevice that is to communicate with the host system can be employed.

Software is hosted on mobile device 100 and host system 250 to implementa VPN. In accordance with this embodiment, the software on mobile device100 implements a connection manager 270 through which communications toand from host system 250 are managed. Connection manager 270 functionsto transmit packets to the host system 250 and receive packets from thehost system 250 via wireless network 200 and shared network 224. Eachconnection to the host system 250 may be made through a selected port ofone or more ports on mobile device 100, to a specific port of one ormore ports on host system 250.

An application 272 or a thread 274 of an application that is executingand resides on mobile device 100 may request that communication withhost system 250 be established. Multiple applications 1 . . . n may beexecuting on mobile device 100, and multiple threads 1 . . . n of anapplication may also be executing, each independently requiringcommunication with host system 250.

For ease of exposition in the following description, applications 272and threads 274 will be referred to collectively as applications 272.Accordingly, the term “application” as used herein in the specificationand in the claims can refer generally to an application 272 or to aspecific thread 274 of an application 272.

An application 272 may register with connection manager 270 if it wishesto communicate with host system 250. Connection manager 270 opensincoming and outgoing connections as required. Each application 272becomes a “packet listener” once registered, and all packet listenersare tracked by connection manager 274.

When an application 272 wishes to send a packet to host system 250, itpasses the outgoing packet to connection manager 270, which chooses theappropriate outgoing connection through which the outgoing packet is tobe sent. This may require selection of an appropriate port on mobiledevice 100 through which to transmit the outgoing packet.

When an incoming packet arrives from host system 250, the incomingpacket is received by connection manager 270, which monitors the portsof mobile device 100. The received packet is then transmitted byconnection manager 270 to a packet cache 276 for storage. Connectionmanager 270 assigns to each received packet a cache-unique identifier,to assist in tracking the packets stored in packet cache 276, and tofacilitate subsequent retrieval of packets (e.g. by applications 272)from packet cache 276. Where the packet cache 276 tracks availableidentifiers, a call may be made by connection manager 270 to packetcache 276 through an appropriate interface thereof, to retrieve andreserve an identifier for the received packet.

After the received packet is stored in packet cache 276, connectionmanager 270 then notifies all packet listeners (i.e. all applications272 that have registered with connection manager 270) that it hasreceived a packet from host system 250. In this embodiment of theinvention, the notification comprises the associated identifier assignedto the received packet.

Each application 272 that is a packet listener can decide what actionsto take upon receipt of the notification. If a particular application272 is not expecting a packet from host system 250, that application orthread may ignore the notification.

However, if a particular application 272 is expecting a packet from hostsystem 250, it can request and retrieve the packet associated with thereceived identifier from packet cache 276, to verify that the packet isintended for that particular application 272.

The verification process performed by the application 272 requesting thepacket, may comprise checking the headers and sequence numbers containedin the packet, for example. If the packet does not pass the verificationprocess, the particular application 272 can wait for another incomingpacket notification from connection manager 270. On the other hand, ifthe packet is successfully verified, the particular application 272 caninform packet cache 276 that the packet is being used, allowing packetcache 276 to remove the packet from its store and to release theassociated identifier.

In this embodiment, packets are retrieved directly from packet cache 276by an application 272 that employs its own verification process (whichmay differ from application to application) to verify packets. However,in a variant embodiment of the invention, packet cache 276 may beadapted to perform verifications on behalf of an application 272, byreceiving data necessary to verify a packet, and releasing the packet tothe application 272 only if the verification is successful. In anothervariant embodiment of the invention, connection manager 270 does notpass the identifier to applications 272 in its notifications, butinstead retains the identifier in memory. Notified applications 272 maythen request and retrieve packets from packet cache 276 indirectlythrough connection manager 270, and verifications may be made either bynotified applications 272, by packet cache 276, or by connection manager270 depending upon the particular implementation.

It will be understood by persons skilled in the art that while certaincomponents (e.g. connection manager 270, packet cache 276) are shown asbeing contained within a single computing device that is to communicatewith the host system, in variant embodiments of the invention, thesecomponents may be distributed over a number of different computingdevices. The different devices over which the components are distributedmay be within the same secure network or may not be within the samesecure network, although configurations of the former type may be moredesirable than the latter from a security perspective in such variantembodiments.

It will also be understood by persons skilled in the art that hostsystem 250 may consist of a single computing device, or may comprisemultiple computing devices. Furthermore, in variant embodiments of theinvention, connection manager 270 may communicate with multiple hostsystems 250, through one or multiple ports on each computing device ofeach host system 250.

Connection manager 270 may also implement additional security mechanismsto be applied to communications made over specific connections to one ormore host systems 250.

Referring to FIG. 6, a flowchart illustrating steps in a method offacilitating communication of packets between one or more applicationsresiding on a first computing device and at least one second computingdevice in an embodiment of the invention is shown generally as 300.

At step 310, applications (e.g. applications 272 or application threads274 of FIG. 5) on a first computing device register with a connectionmanager (e.g. connection manager 270 of FIG. 5). Outgoing and incomingconnections to at least one second computing device on one or more hostsystems (e.g. host system 250 of FIG. 5) may then be established by theconnection manager.

At step 312, the connection manager sends outgoing packets to a hostsystem on behalf of an application, residing on the first computingdevice and registered with the connection manager at step 310.

At step 314, an incoming packet is received by the connection managerfrom a host system.

At step 316, the connection manager transmits the packet received atstep 314 to a packet cache (e.g. packet cache 276 of FIG. 5) forstorage. Connection manager assigns a cache-unique identifier to thestored packet, which can be subsequently used to retrieve the storedpacket from the packet cache.

At step 318, the connection manager notifies all registered applicationsof receipt of the received packet, stored in the packet cache at step316.

At step 320, each registered application determines whether it isexpecting a packet. If a particular application is not expecting apacket, it ignores the notification transmitted by the connectionmanager at step 318.

At step 322, if the registered application is expecting a packethowever, the application then verifies whether the packet is intendedfor the application. In other words, verification is made as to whetherthe packet is a communication from the host system to that particularapplication. In this embodiment, the packet is requested and retrievedfrom the packet cache, using the identifier associated with the packet.The headers and sequence numbers contained in the packet are thenchecked by the application. It will be understood by persons skilled inthe art that additional or different packet verification processes maybe employed by an application.

At step 324, if it is successfully verified that the packet is intendedfor the application, the cache is notified by the application that thepacket is in use. This allows the packet cache to remove the packet fromits store and to release the identifier associated with the packet.

At step 326, execution of the applications on the first computing devicecontinues. Further outgoing packets may be sent to the host system byrepeating step 312 of method 300. As each incoming packet is receivedfrom the host system, steps of method 300 may be repeated commencing atstep 314.

The connection manager in embodiments of the invention can permit thesame application to register multiple threads if the applicationrequires more than one connection. For IPsec, this means that an IKEconnection can be kept separate from an ESP or AH connection. Moreover,multiple IKE, ESP, or AH connections can be opened with differentre-keying times, allowing one connection that is protected by a key thatis soon to expire to exist, while negotiating a new connection under anew key. Accordingly, communications over multiple connections, possiblygoverned by different security parameters, can be facilitated.

In embodiments of the invention where the connection manager manages allincoming packets, the connection manager also functions to better ensurethat each of multiple components (e.g. applications) on a computingdevice receives the proper packets, even where the components may becommunicating with a host over different ports or even over the sameport on the computing device shared by multiple components. Furthermore,each component need not set up its own connections with a host ormultiple hosts, where the connections are managed by the connectionmanager.

The connection manager, when used in combination with the packet cachein embodiments of the invention, can also provide additional defenseagainst denial of service attacks in which a computing device may bebombarded with bogus packets. If components (e.g. applications) are notexpecting a packet, packets received by the connection manager will notbe processed by the components. Old packets can then be periodicallydetected and deleted from the cache.

The steps of a method of facilitating communication of packets inembodiments of the invention may be provided as executable softwareinstructions stored on computer-readable media, which may includetransmission-type media.

The invention has been described with regard to a number of embodiments.However, it will be understood by persons skilled in the art that othervariants and modifications may be made without departing from the scopeof the invention as defined in the claims appended hereto.

1. A system for facilitating communication of packets between one ormore applications residing on a first computing device and at least onesecond computing device, the system comprising: a connection manageradapted to receive packets from the at least one second computingdevice; and a packet cache, coupled to the connection manager, forstoring packets received by the connection manager; wherein, inoperation, upon receiving a packet from a second computing device, theconnection manager transmits the packet to the packet cache for storageand notifies each of the one or more applications of receipt of thepacket; wherein the packet is retrievable from the packet cache by anotified application, and verification that the packet is intended forcommunication to the notified application is made.
 2. The system ofclaim 1, wherein the first computing device is a mobile device.
 3. Thesystem of claim 1, wherein at least one of the connection manager andthe packet cache resides on the first computing device.
 4. The system ofclaim 1, wherein the connection manager is further adapted to transmitpackets generated by the one or more applications to the at least onesecond computing device.
 5. The system of claim 1, wherein an identifieris assigned to each packet transmitted by the connection manager to thepacket cache for storage; wherein in notifying each of the one or moreapplications of receipt of a packet, the identifier associated therewithis employed; and wherein the identifier of a packet facilitates theretrieval thereof from the packet cache by a notified application.
 6. Amethod of facilitating communication of packets between one or moreapplications residing on a first computing device and at least onesecond computing device, the method comprising the steps of: a)receiving a packet from a second computing device; b) transmitting thereceived packet to a packet cache for storage; c) notifying each of theone or more applications of receipt of the received packet; d) uponrequest of a notified application, retrieving the received packet fromthe packet cache; and e) verifying if the received packet is intendedfor communication to the notified application.
 7. The method of claim 6,wherein the first computing device is a mobile device.
 8. The method ofclaim 6, further comprising the steps of generating one or more packetsfor communication to at least one second computing device andtransmitting the generated packets to the at least one second computingdevice.
 9. The method of claim 6, wherein the transmitting stepcomprises assigning an identifier to the received packet transmitted tothe packet cache for storage; wherein in the notifying step, theidentifier associated with the received packet is employed; and whereinthe identifier is used to facilitate the retrieval of the receivedpacket from the packet cache in the retrieving step.
 10. The method ofclaim 6, wherein the request for verification of the received packet ismade by a notified application after the notifying step if the notifiedapplication is expecting a packet to be communicated thereto from thesecond computing device.
 11. The method of claim 6, wherein theverifying step comprises checking headers and sequence numbers containedin the received packet to verify that the received packet is intended tobe communicated to the notified application.
 12. A software applicationfor execution on a mobile device, the application comprising a pluralityof instructions stored on a computer-readable medium, wherein theinstructions, when executed, perform the steps of the method as claimedin claim
 6. 13. A mobile device coupled to at least one remote computingdevice, the mobile device comprising: a connection manager adapted toreceive packets from the at least one remote computing device; and apacket cache, coupled to the connection manager, for storing packetsreceived by the connection manager; wherein, in operation, uponreceiving a packet from a remote computing device, the connectionmanager transmits the packet to the packet cache for storage andnotifies each of one or more applications residing on the mobile deviceof receipt of the packet; wherein the packet is retrievable from thepacket cache by a notified application, and verification that the packetis intended for communication to the notified application is made.